Search

Areas with vulnerable ecological environments often breed many geological disasters, especially landslides, which pose a severe threat to the safety of people’s lives and property in these areas. To aid in landslide prevention and mitigation, an approach combining the coefficient of determination method (CF) and a deep neural network (DNN) were proposed in this study for landslide susceptibility evaluation. The deep neural network can excavate the deep features of samples and improve the accuracy of the susceptibility model. In addition, the logistic regression model (LRM) and support vector machine (SVM) were selected to create landslide susceptibility maps for comparison, which also involved the coefficient of determination method (CF). Based on landslide remote sensing interpretation and field investigations, a spatial database of mudstone landslides in the Xining area was established. Eight different conditional factors, including the elevation, slope, slope aspect, undulation, curvature, watershed, distance from a fault, and distance from a road, in the study area were selected as the evaluation factors to evaluate the susceptibility. The results revealed that four factors (i.e., the ground elevation, curvature, distance from a fault, and distance from a road) had relatively significant influences on the landslide susceptibility in the study area. Finally, the confusion matrix was used to evaluate the accuracy of the results obtained using the three methods, and the optimal result was selected to evaluate the landslide susceptibility in the study area. It was found that the combined CF-DNN method was more suitable for evaluating the landslide susceptibility in this area. Landslide susceptibility zoning was conducted to divide the study area into four sensitivity levels: low (32.65%), medium (35.12%), high (22.44%), and extremely high (9.79%) susceptibility. The high-risk areas were primarily distributed in the high-elevation areas along the eastern edge of the Huangshui Basin.

Explore the features of project that made public

The Multispecies Ovary Tissue Histology Electronic Repository (MOTHER) facilitates comparative studies of female reproductive strategies, enabling the development of computational models to test hypotheses related to ovarian development and female reproduction, and serving as an educational resource thereby reducing the use of animals in research.

Advanced production decline analysis methods have become more economic and efficient options due to technical and time limitations of well-testing operations in shale gas reservoirs. By normalizing rate with material balance pseudo-time, Blasingame type decline analysis can be applied to variable rate/variable pressure drop system, making the methodology more widely applicable. Blasingame decline analysis of variable rate/variable pressure drop case for multi-fractured horizontal well (MFHW) in shale has been less investigated, because of multi-scale storage spaces and multi-flow mechanisms. This article presents a semi-analytical Blasingame decline analysis model incorporating multi-flow mechanisms with shale's modified material balance pseudo-time. Laplace transformation, point source function, numerical discrete method, perturbation method, and Gaussian elimination method were employed to solve the mathematical problem caused by multi-flow mechanisms. Besides, the material balance pseudo-time was modified by considering adsorption and desorption. In this study, a workflow to investigate the effects of properties of hydraulic fracture (fracture half-length, number of fractures and fracture spacing) and multi-flow mechanisms (diffusion and desorption) on production decline behaviors through diagnostic Blasingame type curves is proposed. The results indicate that productivity is greater with a larger scale of fracture treatment, and better desorption of adsorbed gas is also beneficial to production. The decline rates affected by the fracture treatment scale and supplement capacity show two opposite trends, which is caused by interference between the fractures and boundary, respectively. Except that the data in the diffusion early flow period do not match very well, because the use of diffusion coefficient as a constant, the good fitting results on the whole verifies the model's validity and reliability.

Graphene (GN) nanofillers have been widely used to enhance the overall performance of polymer composites due to their various superior properties, which strongly rely on the uniform dispersion and strong interfacial bonding of GN with high-quality polymer matrices. In the present study, the strengthening and functional effects of polydopamine-coated edge-carboxylated graphene (p-ECG) on the mechanical, moisture-barrier and electromagnetic properties of epoxy (EP)-based composites were systematically evaluated. p-ECG was successfully prepared via one-step high-pressure ball milling through the edge-selective functionalization and exfoliation of pristine graphite in the presence of dry ice, followed by synchronous reduction and coating via the mild oxidative polymerization of mussel-inspired dopamine. p-ECG showed prominent advantages of a small sheet size, excellent dispersibility and high chemical reactivity in the EP matrix. Obvious enhancements were achieved in the tensile and flexural properties and moisture-barrier performance of EP composites as well as the interlaminar shear strength (ILSS) and transverse fiber bundle tensile (TFBT) strength of carbon fiber (CF)/EP composites, which confirmed the excellent dispersion and chemically strengthened interfacial bonding of p-ECG in the EP matrix. More importantly, p-ECG introduced onto the surface of desized CF led to significant enhancement in the electromagnetic interference (EMI) shielding capability of CF/EP composites, which was primarily ascribed to the polarization relaxation effect induced by the defects and functional groups in p-ECG as well as the increase in electrical conductivity derived from the "bridging effect" of p-ECG. Specifically, with p-ECG content of 0.5 wt%, the increments in tensile strength, TFBT strength, shielding effectiveness (total, SET) and shielding effectiveness (reflection loss, SER) were as high as 33.3, 34.3, 31.3 and 71.0%, respectively.

In this paper, a kind of high performance concrete (SHPC) was prepared by using sea sand and simulated sea water. The compressive strength of SHPC reached 151.5 MPa. Moreover, SHPC had good carbonization resistance, sulfate resistance, chloride resistance and frost resistance. To investigated its serving performance, SHPC was put in the marine environment for one year. After serving, The changes of SHPC was assessed by appearance, carbonization, compressive strength, Vickers hardness, pH, and the content of free chloride ion. Mercury Intrusion Porosimetry (MIP), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were performed to clarify the corrosion mechanism of SHPC in marine environment. The test results indicated that SHPC had the advantages of good performance and durability. Moreover, the construction period was short and suitable for popularization and application.

Synergetic strengthening effects of epoxy grafted polyurethane (EP-PU) and aminated MWCNTs (MWCNTs-NH2) on mechanical performance of EP-based composites at 77 K were systematically investigated using the tested results at room temperature (RT) as comparisons. EP-PU was successfully synthesized by controlling the reaction between –OH in EP and –NCO in PU prepolymer, which showed the advantages of relatively low viscosity and outstanding chemical miscibility with EP matrix. The most obvious enhancements were achieved with contents of 30 wt% EP-PU and 0.2 wt% MWCNTs-NH2 in tensile, flexural, impact and KIC fracture toughness properties of EP composites as well as flexural properties and interlaminar shear strength (ILSS) of carbon fiber (CF)/EP composites at both RT and 77 K, which confirmed the synergetic strengthening effects of EP-PU and MWCNTs-NH2. Specifically, KIC fracture toughness of EP composites and ILSS of CF/EP composites at 77 K were enhanced by 26.0 and 31.4%, respectively, compared with the corresponding neat composites. The EP-PU component showed β or γ relaxation behavior at cryogenic condition and existed in form of scattered micro-spheres in cured EP matrix due to the phase separation. The riveting and bridging of MWCNTs-NH2 around EP-PU micro-spheres were considered to provide extraordinary synergy on the effective stress diversion and crack propagation inhibition at cryogenic condition through establishing the chemically bonded multi-scale interface.

In practical application of modified gain extended Kalman filter (MGEKF) algorithm, generally used erroneous measured values instead of the real values, so the modified results also contain errors. To solve this problem, this paper proposes an improved MGEKF based on back propagation neural network (BPNN), termed BPNN-MGEKF algorithm. At BPNN training time, it uses measured values as the input, and modified results by true values as the output. So the trained network includes correction of errors, even if input measurement values can be obtained more accurate results. This paper applies the BPNN-MGEKF to single moving station bearing-only position experiment, experimental results showed that: compare to other algorithms, BPNN-MGEKF has a faster convergence speed and higher accuracy.

CCD60, developed by e2v technologies, is a 128x128 pixel frame-transfer back-illuminated sensor using the EMCCD technology. This kind of detector has some attractive characteristics, such as high frame rate, low noise and high quantum efficiency. So, it is suitable for Adaptive Optical Wave Front Sensor (AO WFS) applications. However, the performance of this detector is strongly depended on its temperature. In order to achieve high multiplication gain and low dark current noise, CCD60 should be cooled under -45℃. For this reason, we had designed a cooling system to cool down the CCD60 detector base on thermoelectric cooler. Detail of the design, thermal analysis and the cooling experiment are presented in this paper. The performance of multiplication gain after cooling had been tested too. The result of cooling experiment shows that the thermoelectric cooler can cool the CCD to below -60 °C under air cooled operation and an air temperature of 20 °C. The multiplication gain test tell us the multiplication gain of CCD60 can exceed 500 times on -60℃.

Abstract oTo satisfy the requirement of large telescope, a large aperture focal plane shutte r with aperture size of 3 200mm was researched and designed to realize, which could be star ted and stopped in a relative short time with precise position, and also the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the PWM pulse generated by DSP. Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2s, which meets the performance requirements of large telescope properly. Keywords olarge telescope; shutter; timing-belt, aperture size, closing/open time OMT12-OM100-18 1. INTRODUCTION With the requirement of a large telescope, a large aperture focal plane shutter which is mounted before the CCD is needed, while Camera exposure shutters with apertures in excess of 100 mm are hard to find on the ¯market °. Traditional shutters can be generally assorted to two categories by framework, lamina-type shutter and center-type shutter. The mechanism of lamina-type shutter is motor drive each lamina move by linkage mechanism, which is usually used in camera. The mechanism of center-type shutter is electromagnet control the movement of each blade by linkage mechanism ewhich is mostly used in telescope with small aperture. A ll kinds of shutters can't be simply enlarged with the similar framework. Shutter technology abroad leads us, their structure are complicated, and BONN shutter is famous among them, while the dimension can't satisfy our need. And most shutters abroad used in each large telescope are specifically designed according to different dimensional limitation and speed requirement. They are practically unavailable to our telescope. We have to design a shutter of the whole dimension less than 3 500mm and thinner than 20mm with aperture of 3 200mm, and the open/close time less than 0.2s.

A complementary DNA (cDNA) fragment library from SH-SY5Y cells is constructed using a restriction display polymerase chain reaction (RD-PCR) technique. Messenger RNA (mRNA) is extracted from SH-SY5Y cells and single-strand cDNA synthesised using an anchored oligo primer (dT18). The second strand is produced by nick translation. The double strands are cleaved with the restriction enzyme Sau3AI and the fragments ligated with universal linker. The products are amplified with universal primers and selected primers, ligated into the pMDI8-T vector, and then sequenced. The library constructed contained 136 subgroups, each comprising seven to 12 cDNA fragments. RD-PCR proved a simple, effective way to construct a cDNA library, and this will contribute to the investigation of gene expression in the neuron in future microarray studies.

The oncoprotein E6 of high-risk human papillomavirus (HPV) types promotes cell proliferation and contributes to carcinogenesis of HPV-positive cervical cancer cells. In this study, we used small interfering RNA (siRNA) technology to silence the E6 gene in HPV-18-transformed human cervical cell line HeLa and determined the effects of E6 gene knockdown on the cell by using microarray-based gene expression profiling coupled with gene functional classification with bioinformatics methods. Silencing RNA prepared by siRNA expression cassettes against HPV-18 E6 gene could significantly inhibit E6 gene expression and induce HeLa cells to apoptosis. The microarray analysis identified 359 differentially expressed genes containing 307 up-regulated and 52 down-regulated genes. We analyzed the gene functions and cellular pathways in detail, including cell cycle-related genes, CCNG1 and p21; apoptosis-related genes, CASP4, CASP6, IGFBP3, and DFFA; ubiquitin proteolysis pathway-related genes, UBE3A and UBE2C; keratinocyte differentiation-related genes, KRT4, KRT6E, and KRT18; and antioncogenes, RECK and VEL. In addition, it can be concluded that cellular apoptosis induced by HPV-18 E6 siRNA mainly depends on the P53 and ubiquitin proteolysis pathway to regulate gene expression, consequently inhibiting cell proliferation and promoting cell apoptosis. Meanwhile, activation of antioncogene and upper regulation of immunization-related genes signified the degression of the malignant extent of tumor cells after E6 inhibition. Our approach, which combines the use of siRNA-mediated gene silencing, microarray screening, and functional classification of differential genes, can be used in functional genomics study to elucidate the role of E6 oncogene in the carcinogenesis of HPV-18 and provide some possible targets for clinical treatment and drug development of cervical cancer.

Currently, screening for high-risk human papillomavirus (HPV) infection remains an important health concern throughout the world, because of the close association between certain types of HPV and cervical cancer. In this study, we explore the possibility of using approximately 70mer oligonucleotide microarray for detection and genotyping of HPV. The approximately 70mer type-specific oligonucleotide probes of four different types HPV were designed by using biological software Array designer 2.0, which analyzed the whole genome sequences of HPV and selected optimal probes. These probes were synthesized and printed onto the surface of glass slides in order to prepare a low-density microarray. HPV samples were labeled with fluorescence dyes Cy3 using a method of restriction display polymerase chain reaction (RD-PCR). HPV plasmid DNA was restricted with Sau3A I to produce multiple fragments that were ligated to adaptors subsequently and used as PCR template. PCR labeling was performed with the fluorescently labeled universal primer (Cy3-UP) whose sequence is designed according to the adaptor of the RD-PCR approaches. The labeled samples were hybridized with the oligonucleotide microarray. The scanning results showed that HPV DNA hybridized specifically with multiple spots correspondingly to show positive signals, whereas no signals were detected of all the negative and blank controls. These results demonstrated that approximately 70mer oligonucleotide microarray can be applied to HPV detection and genotyping. The application of RD-PCR in the sample labeling can increase significantly the sensitivity of the assay and will be especially useful for the discriminate diagnosis of multiple pathogens.

A new molecular-baiting method was studied by retrieving targeted gene fragments from an oligonucleotide microarray bait after hybridization. To make the microarray bait, 70-mer oligonucleotides that were designed to specifically represent the SSA1 gene of Saccharomyces cerevisiae were printed on the slide. Samples of the Saccharomyces cerevisiae mRNA were extracted and labeled by the RD-PCR (Restriction Display PCR) method using the Cy5-labelled universal primer, then applied for hybridization. The sample fragments that hybridized to the microarray were stripped, and the eluted cDNAs were retrieved and cloned into the pMD 18-T vector for transformation, plasmid preparation, and sequencing. BLAST searching of the GenBank database identified the retrieved fragments as being identical to the SSA1 gene (from 2057-2541bp). A new method is being established that can retrieve the sample fragments using an oligo-microarray-bait.

Vaccinia virus is a member of the orthopoxvirus group, to which also belongs variola virus, one of the most hazardous pathogens known to man. To establish a model system to detect orthopoxviruses, a vaccinia oligonucleotide microarray is designed, produced and tested. Vaccinia virus is used to test the prepared microarrays. The virus DNA samples in different propagation phases are extracted and hybridised with the oligonucleotide microarray. The results showed that the oligonucleotide microarray can detect vaccinia virus with high specificity and sensitivity.

This study explores the restriction display-polymerase chain reaction (RD-PCR) application of a new chip-based nucleic acid analysis system (Agilent 2100 bioanalyser) in a gene differential expression study. Total RNAs is extracted from Saccharomyces cerevisiae, double-stranded complementary DNA (cDNA) is synthesised by reverse transcription from the purified messenger RNA (mRNA), RD-PCR conducted to obtain the cDNA fragments and bioanalyser and agarose gel electrophoresis compared for the analysis of RD-PCR products. The bioanalyser proved to be faster and more sensitive in separating and detecting gene fragments, and was also able to compare different gene fragments quantitatively. Using this technology, comparison of several differential gene fragments is performed.

Cryogenic optical system undergoes wide temperature change; therefore it must be athermal. That means when the system is cooled down to very low temperature, its imaging property should be kept as good as at room temperature. One way to achieve athermal optical system requires that all optical and mechanical parts in the system be made from same material. An all-reflective cryogenic optical system was thus developed in IOECAS, in which aluminum alloy was utilized to make such a system. This paper describes the key techniques for manufacturing this cryogenic optical system: material selection, forging process of the aluminum alloy blanks, initial machining, heat treatments, and final figuring. The cryogenic test of the developed system proved the validity of the manufacturing process.

An all aluminum reflective optical system was tested to evaluate its optical performances at near liquid nitrogen temperature. A special cryogenic dewar was designed and fabricated with an optical window made of quartz glass on the front wall of the dewar. The optical system under test and a reference plane mirror, which were mounted into the dewar and cooled by liquid nitrogen, formed a double pass interferometric test schema together with a He-Ne interferometer of Fizeau type outside the dewar. The test results showed that there was little differences between the wavefront errors before and after the optical system is cooled, and in both cases the optical system had a diffraction limited imaging quality.

(2002). Re-use of a stripped cDNA microarray. British Journal of Biomedical Science: Vol. 59, No. 2, pp. 112-113.